There are a variety of dampers which are available in the market place today and are different in form and manufacturing principle. For example, certain dampers that are used in the exercise bike are provided with a rotary wheel and a belt by means of which the rotary wheel is tightened to bring about a resistance force. The belt is susceptible to wear or damage. There are also certain dampers which are provided with an electric motor to bring about a resistance force in conjunction with a ratchet wheel. Such electrically-operated dampers as described above are limited in use in that they are virtually useless without a power source.